Adaptive rejection of finite band disturbances - theory and applications

Le chapitre présente les techniques de rejection adpative de perturbation inconnue mais de bande finie. Plusieurs exemples sont mentionnés et l'application au rejet adaptatifs de perturbation inconnues sur une suspension active est décrite en détailThe techniques for adaptive rejection of unknown finite band disturbances are reviewed. Several applications are mentionned and the application to the adaptive rejection of unknown disturbances on an active suspension is presented in detail

Interlaced Direct Adaptive Regulation Scheme Applied to a Benchmark Problem

International audienceDirect adaptive regulation schemes using Internal Model Principle and FIR Youla-Kučera controller parametriza-tion have been extensively used for attenuation of multiple unknown and time varying narrow band disturbances [10], [5], [2].This approach provides very good results but requires a very careful design of the central controller in order to keep the water bed effect on the output sensitivity function at a an acceptable level. To simplify the design of the central controller, an adaptive regulation scheme is proposed in this paper which will incorporate a particular adaptive IIR Youla-Kučera Filter, called ρ-notch structure (the denominator is a projection inside the unit circle of the poles of the model of the disturbance which has roots on the unit circle). The adaptive scheme estimates separately the numerator and denominator parameters of the IIR Youla-Kučera Filter. The use of this approach drastically simplify the design of the central controller and provides even better results than [2] with the advantage to use a single central controller independently of the number of narrow band disturbances. Real-time results obtained on an active vibration control system will illustrate the potential of this approach. Comparison with other approaches applied to the same system are also provided

Indirect Adaptive Attenuation of Multiple Narrow-Band Disturbances Applied to Active Vibration Control

International audienceIn this brief, an indirect adaptive control methodology for attenuation of multiple unknown time varying narrow-band disturbances is proposed. This method is based on the real time estimation of the frequency of narrow-band disturbances using adaptive notch filters followed by the design of a controller using adjustable band-stop filters for the appropriate shaping of the output sensitivity function. A Youla-Kučera parametrization of the controller is used for reducing the computation load. This approach is compared on an active vibration control system with the direct adaptive control scheme based on the internal model principle proposed. Real time experimental results are provided

Modified Direct Adaptive Regulation Scheme Applied to a Benchmark Problem

International audienceA direct adaptive regulation scheme using a FIR Youla-Kučera Filter has been proposed for solving the EJC Benchmark [4] for rejection of multiple unknown and time-varying narrow-band disturbances. Despite the excellent results this approach requires a careful design of the central controller in terms of selection of some of the assigned closed-loop poles. A modified scheme is proposed in this paper which will incorporate a particular adaptive IIR Youla-Kučera Filter. Called ρ-notch structure (the denominator is a projection inside the unit circle) of the model of the disturbance which has roots on the unit circle. The adaptive scheme estimates separately the numerator and denominator parameters of the IIR Youla-Kučera Filter. Stability and convergence proofs are given along with simulation and real-time results. Comparison with results already obtained for the EJC Benchmark are provided. The use of this approach drastically simplify the design of the central controller and provide even better results than [4] with the advantage to use a single central controller independently of the number of narrow band disturbances

Road profile estimation using an adaptive Youla- Kučera parametric observer: comparison to real profilers

International audienceRoad profile acts as a disturbance input to the vehicle dynamics and results in undesirable vibrations affecting the vehicle stability. A precise information of this data is mandatory for a better understanding of the vehicle dynamics behavior and active vehicle control systems design. However, direct measurements of the road profile are not trivial for technical and economical reasons, and thus alternative solutions are needed. This paper develops a novel observer, known as virtual sensor, suitable for real-time estimation of the road profile. The developed approach is carried on a quarter-car model and on measurements of the vehicle body. The road elevation is modeled as a sinusoidal disturbance signal acting on the vehicle system. Since this signal has unknown and time-varying characteristics, the proposed estimation method implements an adaptive control scheme based on the internal model principle and on the use of Youla-Kučera (YK) parametrization technique (also known as Q-parametrization). For performances assessment, estimations are comparatively evaluated with respect to measurements issued from Longitudinal Profile Analyzer (LPA) and Inertial Profiler (IP) instruments during experimental trials. The proposed method is also compared to the approach provided in (Doumiati et al. (2011)), where a stochastic Kalman filter is applied assuming a linear road model. Results show the effectiveness and pertinence of the present observation scheme

Adaptive Road Profile Estimation in Semi-Active Car Suspensions

International audienceThe enhancement of the passengers comfort and their safety are part of the constant concerns for car manufacturers. As a solution, the semi-active damping control systems have emerged to adapt the suspension features, where the road profile is one of the most important factors that determine the automotive vehicle performance. Because direct measurements of the road condition represent expensive solutions and, are susceptible to be contaminated, this paper proposes a novel road profile estimator that offers the essential information (road roughness and its frequency) for the adjustment of the vehicle dynamics by using conventional sensors of cars. Based on the Q-parametrization approach, an adaptive observer estimates the dynamic road signal, posteriorly, a Fourier analysis is used to compute online the road roughness condition and perform an ISO 8608 classification. Experimental results on the rear-left corner of a 1:5 scale vehicle, equipped with Electro-Rheological (ER) dampers, have been used to validate the proposed road profile estimation method. Different ISO road classes evaluate online the performance of the road identification algorithm, whose results show that any road can be identified successfully at least 70% with a false alarm rate lower than 5%; the general accuracy of the road classifier is 95%. A second test with variable vehicle velocity shows the importance of the online frequency estimation to adapt the road estimation algorithm to any driving velocity, in this test the road is correctly estimated 868 of 1,042 m (error of 16.7%). Finally, the adaptability of the parametric road estimator to the semi-activeness property of the ER damper is tested at different damping coefficients

Adaptive Attenuation of Unknown and Time Varying Disturbances - Revisited after ECC13, Zurich

http://technion.ac.il/~issc/Program/pdf/Landau_slides.pdfInternational audienceIn many classes of applications like active vibration control and active noise control the disturbances can be characterized by their frequencies content and their location in a specific region in the frequency domain. The disturbances can be of narrow band type (simple or multiple) or of broad band type. A model can be associated to these disturbances. The knowledge of this model allows to design an appropriate control system in order to attenuate (or to reject) their effect upon the system to be controlled. The attenuation of disturbances by feedback is limited by the Bode Integral and the "water bed" effect upon the output sensitivity function. In such situations the feedback approach has to be complemented by a "feedforward disturbance compensation" requiring an additional transducer for getting information upon the disturbance. Unfortunately in most of the situations the disturbances are unknown and time-varying and therefore an adaptive approach should be considered. The generic term for adaptive attenuation of unknown and timevarying disturbances is "adaptive regulation" (known plant model, unknown and time-varying disturbance model). The paper reviews a number of recent developments for adaptive feedback compensation of multiple unknown and timevarying narrowband disturbances presented at ECC13, Zurich (benchmark on adaptive regulation). Il also reviews recent developments in adaptive feedforward compensation of broad band disturbances in the presence of the inherent internal positive feedback caused by the coupling between the compensator system and the measurement of the image of the disturbance. Experimental results obtained on a relevant active vibration control system will illustrate the performance of the various algorithms presented. Some open research problems will be mentioned in the conclusion

H infinity Gain-scheduled Controller Design for Rejection of Time-varying Narrow-band Disturbances Applied to a Benchmark Problem

A new method for H-infinity gain-scheduled controller design by convex optimization is proposed that uses only frequency-domain data. The method is based on loop shaping in the Nyquist diagram with constraints on the weighted infinity-norm of closed-loop transfer functions. This method is applied to a benchmark for adaptive rejection of multiple narrow-band disturbances. First, it is shown that a robust controller can be designed for the rejection of a sinusoidal disturbance with known frequency. The disturbance model is fixed in the controller, based on the internal model principle, and the other controller parameters are computed by convex optimization to meet the constraints on the infinity-norm of sensitivity functions. It is shown next that a gain scheduled-controller can be computed for a finite set of disturbance frequencies by convex optimization. An adaptation algorithm is used to estimate the disturbance frequency which adjusts the parameters of the internal model in the controller. The simulation and experimental results show the good performance of the proposed control system

H-Infinity Gain-Scheduled Controller Design for Rejection of Time-Varying Disturbances with Application to an Active Suspension System

A new method for H-infinity gain-scheduled controller design by convex optimization is proposed that uses only frequency-domain data. The method is based on loop shaping in the Nyquist diagram with constraints on the weighted infinity norm of closed-loop transfer functions. This method is applied to an active suspension system for adaptive rejection of multiple narrow-band disturbances. First, it is shown that a robust controller can be designed for the rejection of a sinusoidal disturbance with known frequency. The disturbance model is fixed in the controller, based on the internal model principle, and the other controller parameters are computed by convex optimization to meet the constraints on the infinity-norm of sensitivity functions. It is shown next that a gain scheduled controller can be computed for a finite set of disturbance frequencies by convex optimization. An adaptation algorithm is used to estimate the disturbance frequency which adjusts the parameters of the internal model in the controller. The simulation and experimental results show the good performance of the proposed control system